Shu Yamamoto

A Method to Calculate Transient Characteristics of Synchronous Reluctance Motors Considering Iron Loss and Cross-Magnetic Saturation

This paper presents a method to calculate the transient characteristics of synchronous reluctance motor (SynRM). Using an approximate equation suitable for expressing d- and q-axes inductance variation, the authors derive a nonlinear state equation considering both iron loss and cross-magnetic saturation. All electrical motor parameters used for the calculation are measured from tests. Calculation results on transient and steady-state characteristics of a vector-controlled flux-barrier type 1.1-kW SynRM are verified with experimental results.

Maximum Efficiency Drives of Synchronous Reluctance Motors by a Novel Loss Minimization Controller With Inductance Estimator

This paper presents a method to maximize the driving efficiency of synchronous reluctance motors (SynRMs) having cross-magnetic saturation effects. A novel loss minimization controller that generates the optimum current vector is proposed. In the proposed controller, either an off- or online inductance estimator can be adopted. In both cases, the proposed controller can determine the optimum current vector quickly and automatically, and is capable of both maximizing the driving efficiency and also realizing high-precision torque control. In addition, when the proposed controller with the online inductance estimator is employed, a troublesome offline inductance measurement test is omissible. The validity of the proposed method is verified from simulation and experimental results on a 1.1-kW flux-barrier-type SynRM.

Prediction of starting performance of PM motors by DC decay testing method

This paper presents a method to predict the direct- and quadrature-axis operational impedances and starting performance of PM motors by a simple standstill response testing method using a small-capacity DC power supply unit. In this method, not only the starting performance but also the direct- and quadrature-axis synchronous machine constants (synchronous, transient and subtransient reactances) and equivalent circuit constants are calculated. This proposed strategy, tentatively named the DC decay testing method, is carried out on a 3.7 kW 200 V 22 A 100 Hz four-pole interior PM motor with a damper winding. The results measured by on-load tests and those predicted by the proposed method on starting performance demonstrate the validity and usefulness of the proposed method.

Maximum efficiency drives of synchronous reluctance motors by a novel loss minimization controller considering cross-magnetic saturation

This paper presents a method to maximize the driving efficiency of synchronous reluctance motors having cross-magnetic saturation effect. A novel method to calculate the optimum d- and q-axis currents that minimize the loss is proposed. In this method, an approximation equation for expressing inductance variation and a simple repetition method are employed to consider the cross-magnetic saturation. This method can determine the optimum d- and q-axis currents quickly and automatically, without using two-dimensional function tables. By installing this method in a digital signal processor for motor control, the authors realized a novel loss minimization controller capable of considering cross magnetic saturation. The validity of the proposed method is verified from simulation and experimental results on a 1.1kW flux barrier type synchronous reluctance motor.

Universal Sensorless Vector Control of Induction and Permanent-Magnet Synchronous Motors Considering Equivalent Iron Loss Resistance

This paper presents a novel encoder-less vector control strategy which is universally applicable to both induction motors (IMs) and permanent-magnet synchronous motors (PMSMs). A fast rotor flux linkage phase estimator using stator flux linkage information obtained by a high-precision approximation voltage integral with error compensation is shown. Using this estimator, the authors construct a unified position/speed sensorless vector control algorithm taking equivalent iron loss resistance into account. All electrical motor parameters used for the control can be measured from unified off-line tests. The proposed universal sensorless vector control is implemented on a 0.4-kW squirrel-cage IM, a 0.4-kW interior PMSM with concentrated winding, and a 0.3-kW surface PMSM with distributed winding. Experimental results of several driving tests demonstrate the validity of the proposed.

Prediction of starting performance of synchronous motor by DC decay testing method with the rotor in any arbitrary position

This paper presents a novel method to predict the starting performance of synchronous motors. This proposed strategy is based on a simple standstill response testing method using a small-capacity DC power supply unit, tentatively named the DC decay testing method in this paper, and can be applied to standstill synchronous motors with the rotor in any arbitrary position. The proposed testing method is carried out for a 10 kW, 200 V, 31.9 A, 50 Hz, 4P laminated salient-pole synchronous motor with damper winding. The results measured by on-load test and those predicted by the proposed method on starting performance clearly show the validity of the proposed method.

The basic characteristics of two-degree-of-freedom PID position controller using a simple design method for linear servo motor drives

We propose the method of designing two-degree-of-freedom PID position controller for linear servo motor drive systems. In this method, all the parameters of the position controller can be obtained by the basic arithmetical operations from the values of the mover mass, the thrust constant and the desired cut-off frequency of the position control system. This design method is evaluated from the experiments on the position step responses, the disturbance responses, the positioning accuracy and the frequency responses. Besides, the proposed controller is compared with PID and I-PD controllers on the load variations and the disturbance suppression characteristics. The usefulness of the proposed method is proved from these experimental results.

A method to calculate transient characteristics of synchronous reluctance motors considering iron loss and cross-magnetic saturation

This paper presents a method to calculate the transient characteristics of synchronous reluctance motor (SynRM). Using an approximate equation suitable for expressing d- and q-axes inductance variation, the authors derive a nonlinear state equation considering both iron loss and cross-magnetic saturation. All electrical motor parameters used for the calculation are measured from tests. Calculation results on transient and steady-state characteristics of a vector-controlled flux-barrier type 1.1-kW SynRM are verified with experimental results.

Prediction of equivalent circuit parameters of induction motors by DC decay test using voltage-source PWM inverter

This paper presents a new approach to predict the equivalent circuit parameters of induction motors. When the proposed method is employed, all electrical induction motor circuit parameters can be determined by a simple standstill test using a voltage-source PWM inverter. Moreover, the proposed method can measure not only the rotor circuit parameters varying with slip frequency but also the magnetizing reactance considering magnetic saturation. Experimental results on a 5.5kW induction motor demonstrate the validity of the proposed method.

Maximum efficiency drives of interior permanent magnet synchronous motor considering iron loss and cross-magnetic saturation

This paper covers the proposed method to maximize the driving efficiency for interior permanent magnet synchronous motors considering iron loss and cross-magnetic saturation effects. Using a simple repetition calculation method, the proposed method automatically determines the optimum current command in real-time. This method not only maximizes the driving efficiency but also realizes high-precision torque control performance. The validity of this method is verified from experimental results.